Recessed double contact strip base



- lamps 'electric lamps of the type having -lamp' terminals or contacts.

outwardly projecting exposed contact pins on the lamp -bascs.

United States Patent 1 2,899,671 imtnssnn DOUBLE CONTACT srnrr BASE .ioiE. Cridland, Chesterland, Ohio, assignor to General Electric Company, acorporation of New York Application March 1, 1957, Serial No. 643,278 1Claim. (Cl. 339-145) The present invention relates to bases for electricand similar devices and especially for double-ended mounted at the endsof a tubular glass envelope and a pair of spaced apart current inleadwires for each of the' the ends of the envelope. 2,716,739, EugeneLemmers,

lec trodes extending from In the U.S. Patents 2,899,671 Patented Aug.11, 1953 gig. 3 is a front plan view of the base shown in Fig. 2, an

Fig. 4 is a back plan view of the base shown in Figs. 2 and 3. 7'

Referring to Fig. 1 of the drawing, in which like numbers denotelike-parts in all figures, the doubleended electric discharge lampcomprises a tubular sealed glass envelope 1 provided with bases 2 and 3attached to its ends. The bases 2 and 3 are of identical structure and'the internal parts of only the base 3 have been shown in Figs. 2, 3,and 4 for conciseness in description.

The base 3 comprises. an annular metal shell 4, which is suitably madeof sheet aluminum, and a hollow body memberof electrically insulating'materiaLsuch as an organic plastic, in the form of an embossed disk 5.The

. disk-5 may be made of commercial plastic molding compreheatableelectrodes 2:,733,420, Ray E. Marz, and 2,733,421, Dale A. Grovemiller,all of which patents are assigned to theassignee if the presentapplication, bases useful for lamps of the bove type are disclosed andclaimed. A feature of the patented bases is an increased safety factorobtained by ecessing the current inlead wires at each end of the fubularenvelope within a base body of electrically insu- Itat'ing' material andutilizing the recessed wires as the This-eliminated the usual While suchbases have proven eminently satisfactory for safety purposes,difliculties have been encountered in making positive engagementsbetween the wires in the base body of electrically insulating materialand the lamp holder contacts due to the small contact area provided bythe wire terminals of the lamp. Occasionally, due to misalignment of thebases on the lamp envelope or misalignment of the bases and the lampholders, or both,

the wire contacts or terminals would fail to engage the .1-

contacts of the lamp holders when the lamp was inserted in such holders.The lamp would not operate when this occurred.

The principal object of the present invention is to provide a base ofthe above features characteristic of such bases while eliminating theabove difficulties. Other objects and advantages of the invention willappear from the following detailed de scription of species thereof, fromthe accompanying drawing and the appended claims.

In accordance with the invention, the above difiiculties are avoidedwithout reducing the safety factor of such bases and without perceptiblyincreasing the electrical resistance of the path of the low voltageheating current for the preheat electrodes of the lamp by utilizing asthe lamp contacts or terminals metal strips providing comparativelylarge contact areas and securely fastened and recessed within theinsulating body of the base, and by securely fastening, as by soldering,the ends of the current inlead wires of the lamp to the strips to make apositive low resistance electrical connection between the strip contactsand the wires.

In the drawing accompanying and forming part of this specification anembodiment of the invention is shown in which:

Fig. 1 is a side elevational view of a double-ended electric dischargelamp provided with bases embodying the invention.

Fig. 2 is a sectional view on an enlarged scale of one end of the basedlamp shown in Fig. 1.

type which retains all the safety for ing-through the; press passages 14and 15 pounds, such as those comprising phenol-furfural resins orphenolic resins. The inner rim of the shell 4 is embedded in. theperiphery of the insulating disk 5 to mechanically join these base.members, as shown in Fig. 2. The base 3 is sec'ur'edto the end of theglass envelope 1 by a body of basing cement 6.

. The disk 5 has a raised elongated hollow embossment 7 extending acrossits center and projecting outwardly from .thebasefor-engagement withholders (not shown) A centr alppeningor slot 8 extends coinpletely throughftheenibossedportion of the insulating 5. slot-8 hexagonal andslightly elongated in cross-section. The metal. wire. current inleads .9an l 10 to;the ends of theelectrode 1'1 .and extend;

12 of stemliof the glass envelope 1 also extend through wiring passages14 and 15 extending through -the embossed portion -of. the insulatingdisk 5 at the ends ofthe slot '8. When the base is mounted on theenvelope as shown in Fig. 2, the lamp holder contacts are received inthe slot '8 and the inlead wires 9 and 10 extending through the-passages14 and 15 at the ends of the slot 8 are completely insulated from eachother and physically separated from the lamp holder contacts. by thewalls of the-disk 5. I

Electrical connections between the lamp holder contacts received in theslot-8 and the inlead wires 9 and 10 i ntthe wiring passages 14 and 15are made, in accordancewith theprescnt invention, through strip contacts17 and 18 which extend in opposing spaced positionslongitudinally-,aldngtheslot 8 from the front toward the back of thebase, asshown in Fig. 2. The strip contacts are'bent over. at.their endsinto the ends of the wiring I and are thus securely fastened to the disk5. The strip contacts preferably consist of brass and being in stripform provide a larger contact area for engagement by the holder contactsthan the wires 9 and 10 used heretofore as the lamp terminals.

The outer face 19 of the embossment 7 is recessed between the slot 8 andthe outer ends of the passages 14 and 15 a suflicient distance withrespect to the thickness of the bent over portions 20 and 21 of thestrip contacts and the size of the opening in the front face of theembossment as to assure that the said bent over contact portions areprotected from accidental contacts when the base is mounted on the lampenvelope. The safety features characteristic of bases of this type thusare retained in the base of the present invention. The outer bent overportions 20 and 21 of the strip contacts 17 and 18, respectively, whilerecessed within the base, are exposed through the opening in the frontface 19 of the embossment for engagement by lamp holder contacts.

The outer ends of the inlead wires 9 and 10 are connectcd to the outerend portions 20 and 21 of the strip contacts 17 and 18 preferably bybeing soldered thereto as shown at 22 and 23 in Fig. 2 to establish apositive low contact resistance'connection between the contacts 17 and'18 and the wires"9 and "10.

In assembling the base 3 on the lamp envelope the inlead wires 9 andarefirst threaded through thewiringpassages 1'4 and"15, "the base withthe contact-=str1ps 17 and 18 fastened .thereto as described above isthen cemented to the end of the lamp envelope l'in'the usual manner.tendingbeyond the outer ends of the wiring passages 14 and are cut offand the cut ends of "the wires 9 and 10 then soldered to the outer bentover end portions and 2 1 of the strip contacts to complete the mountingof the base 3 on the envelopes. The base 2 is then mounted on theopposite end of the envelope to complete the manufacture of the-lamp."From .the foregoing description of 'a species of base embodying theinvention and the accompanying drawing, ityis'apparent that basesembodying the invention have contacts which are constituted solely bymetal strips, that the inlead wires extending from the end of the lampenvelope are utilized solely for conducting current'from the contactstrips .to the electrodes, that-the contact strips provide a'largercontact area than the line contact provided-by the wires used heretoforeand that the contact strips are 'firmly and immovably fastened inposition in the disk 5.

The lamp shown 'in side elevation in Fig. 1 of the-draw- The excesslength of the wires 9 and 10 cx= ing may be'about 8 feet'in length andabout 1% inches terial is provided on the inner surface of the envelope1 and this material is excited to luminescence by theintense emission of2537 A. wave length radiation of the low pressure mercury vapor dimhargeduring operation of the lamp. Such lamps are commercially available anda species thereof is known in the trade as'the rapid start fluorescentlamp. A low-voltage heater circuit is employed to furnish the heatingcurrent to the preheat electrodes of such lamps and the-strip-contacts17 and 18 soldered to the inlead wires 9 and 10, respectively, in

accordance-with the present invention minimizethe electrical resistancein the heater circuit.

While a preferred species of the invention has been disclosed above itwill be understood that such disclosure is for illustrative purposes andthat it is contemplated that changes may be made in the form and detailsof the base without departing from the invention as defined in theappended claim, for example, the strips may be of other shapes and maybe molded into the plastic insulating body with the contact areasthereof exposed or may be otherwise secured to the body. For example inthe copending application Serial No. 643,430 of Anton M. Krupp et al.,of even filing date herewith and assigned to the assignee of thisapplication an improvement on the base embodying the present inventionis disclosed and claimed in which the strip contacts separate the slot 8from the wiring passages through which the lampinleads are threaded inassembling the base and the lamp envelope and in which the outer bentover portions of the strip contacts are provided with eyelets forreceiving the cut ends of the inlead wires and to which the wire endsare soldered or welded to make a low resistance connectiontherebetween.All such modifications of the of the disk from the back to the front ofsaid base and at the-ends of said slot for receiving inlead wires of thelamp and metal strip contacts clamped to said disk, said strip contactsextending through-said slot at the ends of said slot and having theirend portions bent over into the ends of said wiring passages to securesaid strip contacts to said base, the front face of the embossed portionof said disk between the ends of said slot and the outer ends of saidwiring passages being recessed and exposing the ends of said stripcontacts at the outer ends of said wiring passages for engagement withlamp holder contacts, the depth of said recesses being greater than thethickness of the portions of the strip contacts therein to protect saidstrip contact portions from accidental contacts.

References Cited in the file of this patent UNITED STATES PATENTS1,905,843 Foulke Apr. 25, 1933 2,716,739 Lemmers Aug. 30, 1955 2,733,420Marz Jan. 31, 1956 2,733,421 Grovemiller Jan. 31, 1956

